The SGI IOC4 I/O controller chip drivers are currently all configured by
CONFIG_BLK_DEV_SGIIOC4.  This is undesirable as not all IOC4 hardware features
are needed by all systems.

This patch adds two configuration variables, CONFIG_SGI_IOC4 for core IOC4
driver support (see patch 1/3 in this series for further explanation) and
CONFIG_SERIAL_SGI_IOC4 to independently enable serial port support.
Signed-off-by: NBrent Casavant <bcasavan@sgi.com>
Acked-by: NPat Gefre <pfg@sgi.com>
Acked-by: NJeremy Higdon <jeremy@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>